We have previously produced water soluble amine resins which are Mannich bases by reacting a dihydric phenolic organic compound, preferably a bisphenol, with a stoichiometric deficiency of a diepoxide, and then reacting the product so-obtained, with formaldehyde and secondary amine to provide Mannich base groups. The product with its Mannich base groups was then reacted with epoxide-functional material, preferably a diepoxide, to provide a resinous product which is solubilized in water with the aid of a solubilizing acid.
These materials, and their production, are the subject of our prior application Ser. No. 282,512 filed July 13, 1981. As taught in said prior application, large amounts of formaldehyde and epoxy-functional materials can be used to provide a product having excellent stability, even when so little solubilizing acid is used as provides an alkaline pH in the aqueous solutions which are obtained.
It is desired to maximize the proportion of formaldehyde which is reacted and to distribute the methylol groups formed by this reaction as uniformly as possible. In this way, it is hoped that water solubility will be maximized to decrease the risk of encountering any instability as would cause particle formation or settling in an electrocoating tank.
Also, the reaction sequence set forth in Ser. No. 282,512 leads to complex chemistry, and it is desired to simplify this chemistry.